Segmentation violation when replacing ordered list elements

Description

Security researchers Tyson Smith and Jesse
Schwartzentruber of the BlackBerry Security Automated Analysis Team
used the Address Sanitizer tool while fuzzing to discover a mechanism where
inserting an ordered list into a document through script could lead to a
potentially exploitable crash that can be triggered by web content.

In general these flaws cannot be exploited through email in the
Thunderbird and Seamonkey products because scripting is disabled, but are
potentially a risk in browser or browser-like contexts.